.TH std::dec,std::hex,std::oct 3 "2024.06.10" "http://cppreference.com" "C++ Standard Libary"
.SH NAME
std::dec,std::hex,std::oct \- std::dec,std::hex,std::oct

.SH Synopsis
   Defined in header <ios>
   std::ios_base& dec( std::ios_base& str ); \fB(1)\fP
   std::ios_base& hex( std::ios_base& str ); \fB(2)\fP
   std::ios_base& oct( std::ios_base& str ); \fB(3)\fP

   Modifies the default numeric base for integer I/O.

   1) Sets the basefield of the stream str to dec as if by calling
   str.setf(std::ios_base::dec, std::ios_base::basefield).
   2) Sets the basefield of the stream str to hex as if by calling
   str.setf(std::ios_base::hex, std::ios_base::basefield).
   3) Sets the basefield of the stream str to oct as if by calling
   str.setf(std::ios_base::oct, std::ios_base::basefield).

   This is an I/O manipulator. It may be called with an expression such as out <<
   std::hex for any out of type std::basic_ostream or with an expression such as in >>
   std::hex for any in of type std::basic_istream.

.SH Parameters

   str - reference to I/O stream

.SH Return value

   str (reference to the stream after manipulation).

.SH Example


// Run this code

 #include <bitset>
 #include <iostream>
 #include <sstream>

 int main()
 {
     std::cout << "The number 42 in octal:   " << std::oct << 42 << '\\n'
               << "The number 42 in decimal: " << std::dec << 42 << '\\n'
               << "The number 42 in hex:     " << std::hex << 42 << '\\n';
     int n;
     std::istringstream("2A") >> std::hex >> n;
     std::cout << std::dec << "Parsing \\"2A\\" as hex gives " << n << '\\n';
     // the output base is sticky until changed
     std::cout << std::hex << "42 as hex gives " << 42
         << " and 21 as hex gives " << 21 << '\\n';

     // Note: there is no I/O manipulator that sets up a stream to print out
     // numbers in binary format (e.g. bin). If binary output is necessary
     // the std::bitset trick can be used:
     std::cout << "The number 42 in binary:  " << std::bitset<8>{42} << '\\n';
 }

.SH Output:

 The number 42 in octal:   52
 The number 42 in decimal: 42
 The number 42 in hex:     2a
 Parsing "2A" as hex gives 42
 42 as hex gives 2a and 21 as hex gives 15
 The number 42 in binary:  00101010

.SH See also

   setbase    changes the base used for integer I/O
              \fI(function)\fP
   showbase   controls whether prefix is used to indicate numeric base
   noshowbase \fI(function)\fP
